Further Test ofM1Admixtures in the Decay of2+′ Beta Vibrational States

Abstract

The $\gamma -\gamma$ directional correlation of the 692-123 keV, $2^{+}$′ → $2^{+}$ → $0^{+}$ cascade in ${}_{}{}^{154}{}_{}{}^{}\mathrm{Gd}$ was remeasured with an improved Ge(Li)-NaI system. The spectra in coincidence with the Compton background and the 123-keV photopeak were simultaneously recorded at each angle. The new results averaged with our earlier work yield $A_2=-0.141\mathrm{}\pm 0.022$ and $A_4=0.311\mathrm{}\pm 0.040$. These values are consistent only with the 692-keV transition being essentially pure $E2\mathrm{}$.